This lawsuit is going to backfire because the defendants will simply argue that the benefit is defined as "in-state tuition for California residents", not "in-state tuition". As such, it can be made equally available to citizens, noncitizens and illegals, and there is nothing being offered to illegal aliens that citizens cannot get provided they fall into the defined class ("California residents"). The lawsuit will fail and it'll just make it look like in-state tuition for illegals has some kind of judicial imprimatur.

The way to handle it is through a new law, or failing that, a ballot initiative. Even in California, it ought to be easy to get a majority to agree that an illegal immigrant should not get in-state tuition, while a lifetime legal resident whose parents happen to move out of state during his senior year of high school should get nothing.